The present invention relates to a camera system wherein an external flash is operated in accordance with wireless communication between a camera body and an external flash, and to a camera and a flash device which are employed for this system.
In the above-mentioned system, it is possible to control the operation of an external flash through some signal which is sent from the camera body. As for signals, it is known that an electric wave or a supersonic wave are utilized.
Also, in the above-mentioned system, known is the method making use of a flash light emitted from the camera body as the signals, to control the external flash operation in accordance with the signals. However, if the signal light is projected from a flash of the camera body during an external flash is flashing, the signal light from the camera can not be received at the external flash, because the signal light can not be discriminated from the light emitted from the external flash. Therefore, for example, it is difficult to stop flashing of the external flash by means of a flash light of the camera body.
As one of the methods in order to solve this problem, it is disclosed that the construction of a camera system which is arranged to carry out an intermittent flashing of the external flash so that a signal light from the camera can be caught during the external flash is not flashing, in the prior arts of Japanese Laid-Open Patent Publication No. 58-72931, No. 2-264229 and No. 1-254926.
However, in this kind of a camera system, as various kinds of external flashes are prepared, there are disadvantages as follows when they are used optionally.
Flashes differ each other in luminous characteristics in connection with capacity of its main capacitor, and in raising up feature and maximum flashing duration. Also, the flashes which emit light intermittently differ in the maximum flashing frequency. Accordingly in some cameras of the above-mentioned type, it is feared that the shutter operation does not synchronize with the flashing of an external flash even if the signal to start the flashing is output, and that the signal to stop the flashing of an external flash is output before the proper amount of flash light is attained.
Also, in a flash which emits light intermittently, a long time is needed to complete a flashing operation. Therefore it is impossible to attain proper exposure light, unless the shutter speed is adjusted in accordance with the time needed to complete the flashing operation.